When you create OER, there's an opportunity to make them accessible which shouldn't be missed. The guidelines and tools are out there to help you make your content accessible to everybody, irrespective of any reading / visual / motor impairment(s) or none.
The Universal Design for Learning (UDL) framework by CAST includes "a set of principles for curriculum development that give all individuals equal opportunities to learn, including Students with Disabilities" (AHEAD, 2017).
DCU's Teaching Enhancement Unit offers a Moodle (Loop) page template that complies with UDL principles. The template helps staff to consistently integrate best practice UDL guidelines into their Loop page design. Tour the design elements of the template with this short video and compare your Loop pages against the progression style and box tick checklists available here.
Hilderley (2013) addresses structure, content, and appearance - simple changes like font, font size, colour, alignment, line spacing, as well as alternative text descriptions, meaningful tagging, and text-to-speech capability - with a helpful reference list (see Further resources).